The major areas of effort in this project have been (1) to develop new tracers or other approaches for the study of neurotransmitter function in normal and abnormal physiology; and (2) to apply available tracer methodologies to the study of neuropsychiatric disorders. To these ends the following achievements are notable. PET scans of regional glucose metabolism have revealed that (1)Panic disorder patients have lower left to right hippocampus ratios than normals. This appears to be primarily the result of increased activity in the right hippocampus. (2)Hyperactive adults with childhood onset have reduced global cerebral glucose metabolism. This alteration is most prominent in the areas of the brain related to motor function. (3)Treatment of obsessive-compulsive patients with clomipramine (CMI), the most effective pharmacologic intervention in the disorder, is associated with a reduction in the higher than normal orbitofrontal metabolism observed in patients who are not receiving medications.